The fish in the movie Finding Nemo had made their great escape. After a far-fetched plan and an unlikely set of circumstances, five fish made it out the window and into the ocean. But since they each floated as buoyant prisoners in plastic bags, one asked, “Now what?”

It’s the very question those on the plastic bag ban bandwagon need to ask.

The Great Pacific Ocean Patch, some claim, is the size of Texas. This swirling mass of garbage is said to be full of plastics that will never break down – to the detriment of marine life and eventually of people.

But as many scientists have noted, the amount of garbage is sparse and bears no resemblance to the marine equivalent of a landfill. Not all the garbage is plastic and 60 per cent of what is plastic is discarded fishing gear.

Not even an animal activist like Pamela Anderson could ban fishing, though she might be able to distract fishers for awhile.

So what can be banned?

Plastic bags!

Montreal and Victoria have enacted bans, while Halifax and Edmonton may soon follow. Merits aside, a ban of anything the environmental movement doesn’t like is smart politics for a government that wants to look green. It’s straightforward to enact and has no direct cost to the taxpayer. It has none of the pitfalls of a renewable energy investment that fails in its goals and makes political friends richer and taxpayers poorer. Legislators need not fear a scandal that could ambush them for banning anything. They need only endure the justified grumbles of people who wish they had more freedom and fewer rules.

But if we ban disposable plastic bags, now what?

Here the plot thickens and leads to an ironic conclusion more astonishing than Nemo finding his parents.

Would environmentalists who always oppose the petroleum industry push us back to paper? This would mean higher carbon emissions in the production of the bags and even in their transportation. Paper bags have greater bulk and weight, requiring more trucks burning more diesel fuel just to get the bags to market.

Plastic bags could also be replaced with cotton bags, if poison is your thing. The World Wildlife Fund reports that although cotton accounts for 2.4 per cent of the world’s cropland, it accounts for 24 per cent of the market for insecticides and 11 per cent of pesticides. Plus, cotton is the thirstiest crop ever, needing 5,000 gallons of water to produce a single pound of cotton. A cotton bag is responsible for even more carbon emissions than a paper bag – it would need to be re-used 131 times to have the same carbon emissions as a single-use plastic bag. Besides that, it would consume even more water in washing (without washing, E. coli and other bacteria collect on a re-usable bag).

So the most environmentally friendly solution?

Plastic bags.

The superiority of a permanent plastic bag was demonstrated in a “Life cycle assessment of supermarket carrier bags” study released in 2011 by the Environment Agency of the United Kingdom. The extensive study examined global warming potential, abiotic depletion, acidification, eutrophication, human toxicity, fresh water aquatic eco-toxicity, marine aquatic eco-toxicity, and petrochemical oxidation. The re-usable plastic bag came out on top in all but one category when compared with six alternatives.

Concerns about ocean ecology and garbage can’t justify the demonization of plastic bags.

But we need to stop letting our garbage end up in the water.

Lee Harding is a research associate at the Frontier Centre for Public Policy.

The views, opinions and positions expressed by columnists and contributors are the author’s alone. They do not inherently or expressly reflect the views, opinions and/or positions of our publication.